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Tiny maniraptoran dinosaur from England

From: Ben Creisler

Darren Naish and Steven C. Sweetman (2011)
A tiny maniraptoran dinosaur in the Lower Cretaceous Hastings Group:
Evidence from a new vertebrate-bearing locality in southeast England.
Cretaceous Research advance online publication

In contrast to the Barremian Wessex Formation on the Isle of Wight, the
remains of small theropods are rare in the Berriasian-Valanginian Hastings
Group of the English mainland. Both units are part of the dinosaur-rich
Wealden Supergroup (Berriasian-Aptian) of southern Britain. Here we report
the cervical vertebra of a small dinosaur from the Pevensey Pit at Ashdown
Brickworks, a site located north-west of Bexhill, East Sussex. The pit
yields a rich assemblage of vertebrate fossils from the Valanginian
Wadhurst Clay Formation of the Hastings Group. The new specimen, a
near-complete but water-worn posterior cervical vertebra, is tiny (total
centrum length = 7.1 mm) but evidently from an adult theropod. Its large
hypapophysis, X-shaped neural arch and amphicoelous centrum suggest
referral to Maniraptora, and the subparallel anterior and posterior
articular surfaces imply that it does not belong to a deinonychosaur. The
X-shaped neural arch recalls a similar condition seen in oviraptorosaurs
while the high neural canal/articular surface ratio (0.70) is bird-like.
The specimen is significant in representing the first maniraptoran to be
reported from the Hastings Group but is otherwise indeterminate. By
comparing the specimen to better known maniraptorans and estimating the
proportions of the animal to which it belongs, we suggest that the total
skeletal length of this maniraptoran was somewhere between 16 and 40 cm. It
may therefore have been among the smallest of known Mesozoic dinosaurs.


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